Sylvilagus idahoensis

(Merriam, 1891)

Pygmy Rabbit

G4Apparently Secure Found in 10 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
Least concernIUCN
PSESA Status
HighThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.102656
Element CodeAMAEB04010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassMammalia
OrderLagomorpha
FamilyLeporidae
GenusSylvilagus
USESAPS
Synonyms
Brachylagus idahoensis(Merriam, 1891)Lepus idahoensisMerriam, 1891
Other Common Names
pygmy rabbit (EN)
Concept Reference
Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.
Taxonomic Comments
Originally described as Lepus idahoensis. Included in genus Sylvilagus (see Diersing 1984) but transferred to Brachylagus by Jones et al. (1992) and Hoffmann (in Wilson and Reeder 1993). Cano-Sánchez et al. (2022) returned Brachylagus idahoensis into synonymy with Sylvilagus.

The Washington State (Columbia Basin) population is genetically distinct from the remainder of the species, and is believed to have been isolated for at least 10,000 years, perhaps much longer (USFWS 2001).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2024-07-01
Change Date1998-11-02
Edition Date2024-07-01
Edition AuthorsHunting, K.
Threat ImpactHigh
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of OccurrencesUnknown
Rank Reasons
This species still occupies a relatively large range in the Great Basin and Intermountain region of western North America although that range has decreased as shrub-steppe habitats have been lost and degraded because of fire, grazing, invasion of exotic annuals, and agricultural conversion.
Range Extent Comments
This species occurs from central and southern Oregon and eastern California discontinuously east through southern Idaho, southwestern Montana, and south-central Wyoming south into northwestern Colorado, and west through southwestern Utah and central Nevada, USA. The range extent of this species was estimated at about 700,000 km2 based upon habitat suitability modeling and observations (USGS 2018).
Occurrences Comments
The number of occurrences of this species is unknown.
Threat Impact Comments
The primary threat to this species is loss of sagebrush steppe habitat to a variety of anthropogenic land uses. Loss to agricultural development is considered a threat in Idaho (Roberts 2003). Loss of sagebrush steppe habitat to livestock grazing and invasive plants are considered threats in Utah (Utah Division of Wildlife Resources 2019) and Wyoming (Keinath and McGee 2004) where energy production is also identified as a threat. In some parts of this species range, loss of habitat to urban uses is also a threat. Frequent intense fires likely exacerbated by climate change are also considered a threat to this species. Since the early 1980’s over 26 million acres of sagebrush habitat has burned representing about 15% of habitat for this species (Western Watersheds Project 2023). Replacement or invasion of sagebrush by cheatgrass (Bromus tectorum) has been extensive and reduces habitat suitability for this species and increases the frequency of losses to fire. Extensive grazing has also reduced the extent and quality of habitat for this species across its range by reducing the extent and availability of grasses and forbs consumed by this species. Existing and planned oil and gas development has eliminated and degraded through fragmentation sagebrush habitat for this species especially in Wyoming where about 42% of habitat for this species affected by oil and gas development (Western Watersheds Project 2023).
Ecology & Habitat

Habitat

This rabbit generally occurs in dense stands of big sagebrush growing in deep loose soils. It is highly dependent on sagebrush for food and shelter throughout the year. Unlike most other rabbits, it digs burrows, which are around 3 inches in diameter; a burrow may have multiple entrances. Pygmy rabbits occasionally use of burrows abandoned by other species and may occur in areas of shallower or more compact soils if these sites support sufficient shrub cover (USFWS). Microhabitat for nesting is poorly known; burrows have been excavated, but no nests have been found (Green and Flinders 1980).

In southwestern Wyoming, pygmy rabbits selectively used dense and structurally diverse stands of sagebrush that accumulated a relatively large amount of snow; the subnivean environment provided access to a relatively constant supply of food and provided protection from predators and thermal extremes (Katzner and Parker 1997).

Ecology

Predators include: weasels, coyotes, owls, and likely other carnivorous mammals and birds.

Reproduction

Breeding period extends from spring to early summer. Gestation lasts probably about 27-30 days (Green and Flinders 1980). Adult females produce 2-3 litters per year, with 4-8 young per litter (Reid 2006).
Terrestrial Habitats
Shrubland/chaparralDesert
Other Nations (1)
United StatesN4
ProvinceRankNative
WashingtonS1Yes
OregonS2Yes
NevadaS3Yes
WyomingS2Yes
CaliforniaS3Yes
ColoradoS1Yes
IdahoS3Yes
MontanaS3Yes
UtahS3Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentRestricted (11-30%)Slight or 1-10% pop. declineHigh (continuing)
1.1 - Housing & urban areasRestricted (11-30%)Slight or 1-10% pop. declineHigh (continuing)
2 - Agriculture & aquacultureLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
2.1 - Annual & perennial non-timber cropsLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
2.3 - Livestock farming & ranchingLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
3 - Energy production & miningRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
3.1 - Oil & gas drillingRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
3.3 - Renewable energyRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
7 - Natural system modificationsLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
7.1 - Fire & fire suppressionLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesPervasive (71-100%)Moderate or 11-30% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesPervasive (71-100%)Moderate or 11-30% pop. declineHigh (continuing)
11 - Climate change & severe weatherPervasive (71-100%)Slight or 1-10% pop. declineHigh (continuing)
11.2 - DroughtsPervasive (71-100%)Slight or 1-10% pop. declineHigh (continuing)

Roadless Areas (10)
California (2)
AreaForestAcres
Glass MountainInyo National Forest52,867
Mono CratersInyo National Forest7,115
Idaho (2)
AreaForestAcres
Italian PeakCaribou-Targhee National Forest141,158
Lemhi RangeSalmon-Challis National Forest308,533
Montana (1)
AreaForestAcres
Italian PeakBeaverhead-Deerlodge National Forest90,401
Nevada (2)
AreaForestAcres
South SchellHumboldt-Toiyabe National Forest125,614
Table Mtn. - EastHumboldt-Toiyabe National Forest87,789
Wyoming (3)
AreaForestAcres
0401035Ashley National Forest5,465
0401036Ashley National Forest6,309
West Slope WindsBridger-Teton National Forest143,252
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